U.S. Pat. No. 6,602,515, copending application Ser. No. 10/022,343, filed Dec. 20, 2001, and U.S. Pat. No. 6,699,463 describe compounds of general formulae i, i′ and i″, respectively.

with A and R groups as defined more particularly below. These compounds have sunscreen activity, i.e., they have a chromophoric moiety which absorbs within the ultra violet range from 290–400 nm. These compounds also exhibit antioxidant properties which preserve other UV absorbers within sunscreen formulations. They are typically used in sunscreen formulations in amounts of 2 to 10 wt % based on the total weight of the sunscreen formulation.
Light is a form of energy. Therefore molecules that are able to absorb UV and visible light such as organic colorants, dyes, antioxidants, fragrances, & flavor ingredients, can be elevated to a higher energy level (excited state) upon absorption of radiation. In this state, molecules are more reactive than in the ground state. They may react with other molecules or breakdown into lower energy degradation products resulting in complete loss of product integrity, color loss, malodor, viscosity changes etc. The probability of reaction or decomposition is directly related to the length of time molecules remain in the excited state.
The absorption of UV light by UV absorbing chromophores does not block all potential degradation pathways for photosensitive compounds. Another approach to avoid (UV-) light induced decomposition is the quenching of excited chromophores. Quenching of excited chromophores reduces the lifetime of excited states thereby reducing the side reactions of excited state intermediates. This results in an extended shelf life for formulated products. Combining UV-light absorbing capability with the ability to quench the excited state within a single molecule is desired.